Small scale high speed turbomachinery

ABSTRACT

A small scale, high speed turbomachine is described, as well as a process for manufacturing the turbomachine. The turbomachine is manufactured by diffusion bonding stacked sheets of metal foil, each of which has been pre-formed to correspond to a cross section of the turbomachine structure. The turbomachines include rotating elements as well as static structures. Using this process, turbomachines may be manufactured with rotating elements that have outer diameters of less than four inches in size, and/or blading heights of less than 0.1 inches. The rotating elements of the turbomachines are capable of rotating at speeds in excess of 150 feet per second. In addition, cooling features may be added internally to blading to facilitate cooling in high temperature operations.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/308,880, filed Feb. 26, 2010, the content of which is incorporated byreference herein in its entirety.

GOVERNMENT LICENSE RIGHTS

This invention was made with government support under NationalAeronautics and Space Administration (NASA) Phase II Small BusinessInnovation Research (SBIR) contract NNX1OCA89C. The government hascertain rights in this invention.

BACKGROUND

This application relates to turbomachinery and in particular to highspeed, small scale turbomachinery.

High-speed turbomachinery is used in many applications, including highpressure liquid centrifugal pumps, high-speed centrifugal gascompressors, gas turbines, liquid turbines, rocket turbopumps,car-engine turbochargers, aircraft auxiliary power units, jet engines,and stationary power generation devices. These devices usually includeone or more rotating devices that transmit power from a rotating shaftinto a working fluid, increasing the energy contained in the workingfluid, or extract power from a working fluid and transfer that powerinto a rotating shaft, reducing the energy contained in the workingfluid.

Turbomachines typically have rotating elements with outer diameters inthe range of 3 inches (for turbochargers) up to several feet (for largejet engines, steam turbines, or hydroelectric turbines). However,similar devices have generally not been successfully designed orconstructed that can operate at high speeds when the outer diameters ofthe rotating elements are one and a half inches or smaller. Design ofdevices in this size range has not succeeded, in part, because it is notcurrently possible to manufacture turbomachines with the precision andsmall features required to maintain high performance operation at thesescales and speeds.

SUMMARY

To enable a small scale, high speed turbomachine, embodiments of theinvention include turbomachine designs and techniques for manufacturingthe turbomachine. The turbomachine is manufactured by bonding stackedsheets of metal foil, each of which has been pre-formed to correspond toa cross section of the turbomachine structure. The turbomachines includerotating elements that are capable of operating at tip speeds in excessof 150 feet per second. Using this process, turbomachines may bemanufactured with rotating elements that have outer diameters of lessthan four inches in size, and/or blading heights of less than 0.1inches.

The turbomachines may also include static structures, which may be addedafter bonding through machining, or also created through the samestacked sheet bonding process. Embodiments of the invention also includedesigns for integrated cooling components to assist in bringing down theoperating temperature of a turbomachine, as well as labyrinth seals thatmay be used, optionally, in conjunction with turbomachines of any size.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a cross sectional view of a turbomachine.

FIG. 2 a illustrates a turbomachine with a pump and a turbine, inaccordance with one embodiment.

FIGS. 2 b and 2 c show a turbomachine with two alternate embodiments ofa rotating element.

FIG. 3 illustrates a sample three dimensional model of a rotatingelement, and a sample set of etched metal foil sheets matching threedifferent cross sections of the sample rotating element at differentlocations along the axis, according to one embodiment.

FIGS. 4 a and 4 b illustrate example cross-sections of turbomachinerotating elements manufactured by stacking metal foil sheets that areperpendicular to the rotation axis, in accordance with one embodiment.

FIGS. 4 c and 4 d illustrate an example cross sections of a rotatingelement of a turbomachine manufactured by forming metal foil sheets intoconical layers and stacking these layers, according to one embodiment.

FIGS. 4 e and 4 f illustrate two example cross-sections of aturbomachine rotating element manufactured by stacking metal foil sheetsthat are parallel to the rotation axis, in accordance with oneembodiment.

FIG. 4 g illustrates an example foil sheet prior to stacking, accordingto one embodiment.

FIG. 4 h illustrates a rotating element of a turbomachine after excessmaterial has been removed, whereby the rotating element was made fromstacking metal foil sheets that are parallel to the rotation axis,according to one embodiment.

FIGS. 4 i and 4 j illustrate example cross sections of a rotatingelement of a turbomachine made from stacking metal foil sheets incircumferential layers around the axis of rotation, in accordance withone embodiment.

FIG. 4 k illustrates a portion of a typical circumferential sheet, inaccordance with one embodiment.

FIG. 5 a illustrates an example cross section of a static structure of aturbomachine made from stacking and bonding metal foil sheets to defineinternal flow structures, in accordance with one embodiment.

FIG. 5 b illustrates a sample sheet for creating a static structure pumpdischarge volute, according to one embodiment.

FIG. 5 c illustrates a static structure of a turbomachine after excessmaterial has been removed, whereby the static structure is made fromstacking and bonding metal foils sheets, according to one embodiment.

FIG. 6 illustrates a flow diagram for a process for manufacturingrotating elements and static structure of a small scale, high speedturbomachine, according to one embodiment.

FIGS. 7 a and 7 b illustrate example cross sections of a rotatingelement of a turbomachine that includes internal cooling features, wherethe rotating element and the internal cooling features area made fromstacking and bonding metal foil sheets, according to one embodiment.

FIG. 7 c illustrates a portion of an example foil sheet prior tostacking, where the example foil sheets include features used forinternal cooling, according to one embodiment.

FIGS. 7 d and 7 e illustrate portions of example foil sheets prior tostacking, where the example foil sheets include features used forinternal cooling, according to other embodiments.

FIGS. 8A, 8B, and 8C illustrate examples of labyrinth seals inaccordance with several different embodiments.

The FIGs. depict various embodiments of the present invention forpurposes of illustration only. One skilled in the art will readilyrecognize from the following discussion that alternative embodiments ofthe structures and methods illustrated herein may be employed withoutdeparting from the principles of the invention described herein.

DETAILED DESCRIPTION

Turbomachine Elements

FIG. 1 illustrates a cross sectional view of a turbomachine. Theturbomachine 100 includes a first rotating element 101 that increasesthe enthalpy of the working fluid that passes through it. An example ofa first rotating element 101 may be a compressor, pump, or impeller, andmay include additional stages or an inducer. For simplicity, the firstrotating element 101 will be referred to herein as a pump. The pump 101is powered by a second rotating element 102 that decreases the enthalpyof the turbine drive fluid that passes through it. An example of asecond rotating element is a turbine. For simplicity, the secondrotating element 102 will be referred to as a turbine.

Turbine 102 powers pump 101 via a shaft 103. Typically, pump 101,turbine 102, and the shaft 103 are different physical components. Theworking fluid enters the turbomachine at the entrance 115, passesthrough blading 104, and is collected in exit device 105. The turbinedrive fluid enters at inlet 106, passes through turbine inlet guidevanes 107, passes through turbine blading 108, and exits after passingby one or more struts 109.

In existing turbomachines, there is a often a close clearance 110between the blading 104 of pump 1 and the external housing 116. Theclose clearance 110 forms a forward seal. The forward seal minimizesleakage or errant flow of the increased pressure fluid from the exitdevice 105 back into the incoming working fluid. Rear seal 111 minimizesleakage from the exit device 105 of pump 101. Similarly, rear seal 112minimizes leakage from turbine flow path. Bearings 113 and 114 allow thepump 101 and turbine 102 and shaft 103 to rotate at high speed whilestill remaining centered on the centerline axis 117.

In existing turbomachines, rotating elements are typically assembledfrom multiple components that are mechanically fastened together, thesecomponents typically including multiple individual blades and a mountingdisk. In some cases the rotating element may be a single piece. Theindividual components or singe piece element are typically machined fromsingle pieces of material or cast to near-final shape and then machinedto final shape. Turbomachines have complicated internal geometries. Inorder to meet standard turbomachine efficiencies, the geometries of therotating elements are precisely configured. For example, the shape ofthe blading and fluid flow paths is carefully selected to achieve thedesign performance goals of the machine, and changes to the shape willoften reduce performance. As another example, variance in the clearancebetween the blading of a rotating element and the external housing orany added shrouding may affect the efficiency of the turbomachine.

In most turbomachines, the smallest clearance that is feasible tomanufacture and maintain during operations is preferred to maximizeefficiency and performance. In many cases, if it is feasible tomanufacture the turbomachine with a co-rotating shroud such that thereis zero clearance, this is done. However, in some types ofturbomachines, usually compressors or pumps, a small clearance betweenthe blading and the casing allows some amount of leakage flow betweenthe higher and lower pressure side of the blades, which can increaseturbomachine efficiency relative to a shrouded design. Too much or toolittle flow decreases efficiency. Further, temperature changes may causethe material making up either or both of the rotating element and thestationary casing to expand or contract, changing the clearance betweenthe two and therefore the performance of the turbomachine.

Some turbomachines include shrouds in between the housing and therotating element in order to maintain the efficiency of theturbomachine. Some large scale turbomachines make use of shrouding tobalance out axial thrust, which can cause problems at the higherpressures readily achieved by larger turbomachines pumping high densityfluids such as liquids. As the pressure on the rotating element goes up(e.g., 500 psi and higher), shrouding can improve the balance ofpressure between the inlet and outlet sides of the rotating element,greatly reducing the axial force on the turbomachine's bearings.

As a turbomachine gets smaller in size, it becomes more difficult tomanufacture an efficient turbomachine with a small amount of clearancebetween the blading of the rotating element and the external housing. Insuch cases adding a shrouding to eliminate the clearance would improveperformance, but at very small sizes, it also becomes more difficult tomanufacture a rotating element with an integral shroud using techniquesfamiliar to those skilled in the art. In one embodiment, a smallturbomachine and a process for manufacture includes a shrouded rotatingelement, which allows a relatively large clearance between the outsideof the shroud and the stationary casing without substantially reducingthe efficiency and performance. The shrouding of the turbomachineincreases, rather than decreases, the efficiency and performance of thesmaller scale rotating elements. In one embodiment, well-controlledsmall gaps may be inserted between the co-rotating shrouding and theblading to slightly further improve performance. In one embodiment, theclearance between the blading and the shroud, along more than half thelength of the blading in the primary flow direction, is less than fivepercent of the height of the blading.

In one embodiment, the turbomachine is between 0.5 and 4 inches,inclusive, in rotating element outer diameter. In one embodiment, theturbomachine is between 0.4 and 3 inches, inclusive, in rotating elementouter diameter. In one embodiment, a turbomachine is manufactured thatcomprises a rotating element 1 inch in diameter that rotates at 55,000RPM and pressurizes water. In various embodiments of the turbomachine,the materials of construction and the shape of the blading will beselected so that a rotating element of the turbomachine is able torotate at a particular maximum speed. In one embodiment, this maximumspeed of a rotating element is greater than 150, 250, 350, 450, 550 or800 feet per second. In one embodiment, the turbomachine pressurizes aliquid fuel. In one embodiment, the turbomachine pressurizes a liquidoxidizer. In one embodiment, the turbomachine has at least two rotatingelements on a common shaft and pressurizes both a liquid fuel and aliquid oxidizer in separate rotating elements. In one embodiment, theturbomachine does not utilize a turbine, but contains at least onerotating element to pressurize a fluid and is powered by a high-speedelectric motor. In one embodiment, the turbomachine is a rocketturbopump. In one embodiment, the turbomachine is a gas turbine engine.

In one embodiment, the blading of the rotating elements has height atthe outer radius of 0.020 inches or less. In one embodiment, the bladinghas height at the outer radius of 0.012 inches. In one embodiment, theblading has height of 0.050 inches at the tip. In one embodiment, theblading has height of 0.1 inches at the tip. In one embodiment, thepartial gap between the co-rotating shrouding and the blading of therotating element is less than two percent of the blading height. In oneembodiment, the partial gap between the co-rotating shrouding and theblading of the rotating element is less than one percent of the bladingheight.

FIGS. 2 a-2 c illustrate cross sectional views a small scale, high speedturbomachine, in accordance with several embodiments of the invention.FIG. 2 a illustrates a turbomachine with a pump 221 and a turbine 222,in accordance with one embodiment. The pump 221 may be a pump orcompressor, and may comprise more than one stage. The turbine 222 is aradial-inflow turbine, joined to the pump 221 via a shaft joint 223. Inone embodiment, the pump 221 is a single mechanical part, including ahollow shaft 224 next to the entrance 230 where the working fluid isintroduced. The entrance 230 feeds into blading 225 and/or 226, andshroud 227. The shroud 227 and hollow shaft 224 eliminate the relativelylarge gap that would otherwise occur between blading 225 and/or 226 andthe turbomachine stationary casing 270. Turbine 222 similarly includesblading 228 and a shroud 229.

In one embodiment, blading 225 within hollow shaft 224 may optionallyserve as an inducer to provide initial pressurization of the workingfluid in order to limit cavitation at the fluid entrance to blading 226.The pressurized working fluid then passes through the pump blading 226where it is further pressurized.

The working fluid flows from blading 226 through diffusing section 231.The diffusing section 231 may optionally include stationary blading (notshown). The working fluid is collected in exit passages 232 fordistribution as an input to an engine (not shown), for example to arocket engine.

Turbine inlet chamber 233 receives a turbine drive fluid from a source,for example an engine. Turbine inlet chamber 233 accelerates the drivefluid through turbine inlet guide vanes 234 and through turbine blading228. The acceleration of the drive fluid through blading 228 extractspower which is transmitted through shaft joint 223 back to pump 221. Thedrive fluid collects at exit location 235, and may be provided back tothe engine for further use or removed as exhaust.

In one embodiment, the turbomachine includes two or more bearings 238and 239. The bearings 238 and 239 may be bearings of conventional size,and do not need to be reduced in size to match the smaller scale ofembodiments of the turbomachine. In one embodiment, the turbomachineincludes two or more seals 236 and 237 in order to prevent leakage ofworking fluid outside the device or to other areas of the device, forexample at the exit 232 of the pump. This is particularly beneficial ifthe working fluid is under high pressure.

FIGS. 2 b and 2 c show two alternate embodiments of turbine 222. In theembodiment of FIG. 2 b, turbine 240 includes extended radial inflowblading 241 and an extended shroud 242 permitting the addition of axialseal 243 to turbine 222. The additional axial seal 243 prevents leakageof turbine drive fluid outside the device or to other areas of thedevice. The extended blading 241 allows for a more gradual extraction ofenergy from the working fluid, which could improve the efficiency of theturbine relative to turbine 222 with non-extended blading 228.

In the embodiment of FIG. 2 c, axial-flow turbine 245 includes axialflow blading 246, axial flow turbine inlet guide vanes 247 and exitvanes 248, as well as two additional seals 249 and 250 to turbine 222.The additional seals 249 and 250 prevent leakage of turbine drive fluidoutside the device or to other areas of the device. This embodiment mayallow for higher speed operation than turbine 222 since the blading 245is radially outward from the turbine disk, while blading 228 iscantilevered off of the disk of turbine 222. This embodiment is alsomore suited towards including an additional turbine stage or stagesfollowing stationary blading 248.

Process for Manufacturing Turbomachines

FIGS. 3, 4 a through 4 k, 5, and 6 illustrate a process formanufacturing elements of a small scale, high speed turbomachine,according to one embodiment. The process of manufacture has no inherentlimit on the lower bound for either of the rotating elements or theblading heights of those rotating elements. In addition to manufacturingthe rotating elements, the process is also able to manufacturestationary elements of the turbomachine.

Traditional techniques for building turbomachines at small sizes runinto problems when trying to manufacture turbomachines with sufficientprecision, for example for the blading clearance between blading and ashroud or housing. In order to construct a small scale turbomachine asdescribed above, the process includes diffusion bonding or brazing ofseparate metal foil sheets, each etched with a thin cross section of thestructure of a rotating element of a turbomachine.

FIG. 3 illustrates a sample three dimensional model of a rotatingelement 310, and a sample set of etched metal foil sheets 318 matchingthree different cross sections 312, 314, 316 of the sample rotatingelement at different locations perpendicular to its axis of rotation,according to one embodiment. The three dimensional model 310 is shownwith its shrouding removed so that individual blades 311 may be seen.The metal foil sheets are thin slices of material pre-formed to haveshapes of two dimensional slices of the turbomachine cut or etched intothem, such that sheets 313 correspond to axial location 312; and sheets315 correspond to axial location 314, and sheets 317, with blading 319,correspond to axial location 316. The metal foil sheets may bepre-formed by chemical etching, or by other methods such as machining,water-jet cutting, or laser-cutting. Other methods of pre-forming may beused as well. Once sheets are pre-formed, the final blading is formed bystacking (or layering) the metal foil sheets on top of one another in aproperly aligned fashion, and then bonding the sheets together. In oneembodiment, the sheets are between 0.0001 and 0.032 inches thick,inclusive.

FIGS. 4 a and 4 b illustrate example cross-sections of rotating elementsof a turbomachine manufactured by stacking metal foil sheets such thatthe sheets form planes perpendicular to the axis of rotation 413 and423, in accordance with one embodiment. FIG. 4 a depicts a pump impellerof a turbomachine, according to one embodiment. FIG. 4 b depicts aradial in-flow turbine rotor of a turbomachine, according to oneembodiment, or a radial out-flow turbine rotor, according to anotherembodiment. In FIGS. 4 a and 4 b, the layers of pre-formed metal foilsheets 410 and 420 define internal geometries such as blading 416 and426, as well as the non-bladed center of rotating element 415. Otherinternal features created using the layers include impeller inlet flowarea 414, impeller blading leading edge 415, and turbine outlet hub 424.

In one embodiment, thin layers 410 and 420 are combined with one or morethicker plates such as 411, 412, 421 and 422 on one or both sides of thelayers. In this embodiment, these plates 411, 412, 421 and 422 arelocated in regions of axial extent of the rotating element that do notcontain complex internal passages or blading, and can be bonded intoposition with the thin sheets 410, 420, reducing the total number ofsheets that are processed prior to bonding the initial part.

The ordered and stacked cross sections of the turbomachine (or staticstructures) are fused together into a single part through a bondingprocess. In one embodiment, the bonding process is a diffusion bondingprocess. In another embodiment, the bonding process is a brazingprocess. Machining or other techniques may be used to cut away excessmaterial outside of the final part boundaries 417 and 416 in order tochange the shape of the turbomachine rotating element, or expose theinternal flow passages, or produce features, e.g. 418 and/or 428 thatallow the rotating element to be aligned and coupled to other rotatingelements.

FIGS. 4 c and 4 d illustrate an example cross section of a rotatingelement of a turbomachine manufactured by forming metal foil sheets intoconical layers and stacking these layers, according to one embodiment.In the example embodiment of FIG. 4 c, a rotating element of aturbomachine is manufactured by shaping, forming, and stacking metalfoil sheets such that the sheets form partial conical shells where theaxes of the shells are coincident with the axis of rotation 431. In oneembodiment, the sheets are stacked at an angle that is not 0 or 90degrees with respect to the axis of rotation. The thin conical shells430 are formed from flat sheets 440 illustrated in FIG. 4 d, accordingto one embodiment. The flat sheets 440 are pre-formed such that anarc-segment of angle 443 is removed so that as the two edges on eitherside of angle 443 are brought together, a conical shell is formed. Theflat sheets 440 also include center holes 444. The flat sheet includesfeatures 442 that define the solid blading of the eventual rotatingelement, as well as features 441 that define the fluid flow path betweenthe blades within the eventual rotating element.

In one embodiment, a solid base 432 is shaped to receive the conicalshells. The base 432 may be connected to an alignment pin 433 along therotation axis 431, and an alignment cylinder 434. The alignment pin 433and alignment cylinder 434 are used to maintain the conical shells inaxial alignment while they are stacked to form the internal blading 436.Care is taken to ensure appropriate circumferential alignment of theblading elements, while also ensuring that individual shells are rotatedaround the axis such that the seams separating angle 443 are distributedcircumferentially around the element. Once the shells are in place, asolid top 435, shaped to fit closely to the internal contour of theconical shells is inserted, and the shells can be bonded together. Oncethe shells are bonded together, excess material can be removed bymachining or other means to the final external contour 437 of theelement.

FIGS. 4 e and 4 f illustrate example cross-sections of a rotatingelement of a turbomachine manufactured by stacking metal foil sheets 450such that the sheets 450 form planes parallel to the axis of rotation451, in accordance with one embodiment. FIG. 4 e shows a cross sectionthrough the axis of rotation 451, and FIG. 4 f shows a cross sectionperpendicular to the axis of rotation 451. The blading 452 is defined inthose layers and locations within the boundary 453, but outside of theboundary of 454 which represents the center non-bladed portion of therotating element. After the layers are stacked and bonded together,excess material may be removed. In one embodiment, illustrated in FIG. 4f and in the upper half of FIG. 4 e, excess material is removed outsideof contour 455 to produce a rotating element without a shroud. Inanother embodiment, illustrated in FIG. 4 f and the lower half of FIG. 4e, excess material is removed outside of contour 456 to produce arotating element with a co-rotating and integral shroud.

FIG. 4 g illustrates a single foil layer from within layers 450,according to one embodiment. Regions 461 are removed to create flowareas, and regions 462 remain to create the blading. Region 463 remainsto create the hub of the rotating element. FIG. 4 h depicts anshroudless inducer, a rotating element 465 that would result fromutilizing contour 455 for removing excess material, according to oneembodiment. This inducer includes blading 463, defining flow area 464.

FIGS. 4 i and 4 j illustrate example cross-sections of a rotatingelement of a turbomachine manufactured by stacking metal foil sheets 470such that the sheets form cylindrical shells each concentric with theaxis of rotation 473, in accordance with one embodiment. In oneembodiment, this rotating element would be an axial-flow turbine. Thesheets are wrapped around cylinder 471, such that their ends meet atseam 474 (though in other embodiments the seams of each layer need notbe co-incident), and outer solid thick-walled cylinder 472 is placedaround the sheets to contain them. Care should be taken to ensure properalignment of the layers. The sheets and inner and outer cylinders arethen bonded together to define blades 475 and flow path areas 476internal to the structure. Material is then removed to contour 478 toexpose the blades and flow areas. FIG. 4 k depicts, for one embodiment,the shape of one sheet 480 before it is formed into the cylindricalshell, including blades 482 and flow path 481. In one embodiment, theshape of the blades would be different in each layer to allow for agradual change in blade incidence and turning angle from the blade hubto blade tip. In one embodiment, the flat sheets may be formed intoaxisymmetric shells that are neither conical nor cylindrical prior tobonding.

Note that in all subfigures FIG. 4, the thickness of sheets 410, 420,430, 450, 470 is typically enlarged for clarity and not to scale. Someembodiments would utilize many more sheets than can be illustratedeffectively.

FIG. 5 represents an example static structure, according to oneembodiment: a pump discharge volute. FIG. 5 a illustrates an examplecross section of an example pump discharge volute of a turbomachine. Thestatic structure is manufactured by stacking and bonding metal foilsheets such that the sheets form planes perpendicular to the axis ofrotation 525 of the rotating elements within the static structure. Inone embodiment, the sheets are etched to define the internal flowfeatures of the primary working fluid. In one embodiment, these flowfeatures include the collection volute 511, central hole 513, anddiffusion section 512, which in some embodiments will include internalblading. In one embodiment, additional solid blocks of material 515,516, with central holes 517, 518, are stacked on either side of thesheets 510, and the whole stack is bonded together. In one embodiment,material is removed to contour 519, creating inlet fitting 520, matingsurfaces 521 and 522 for mounting to other parts of the staticstructure, and impeller contour 523.

FIG. 5 b illustrates a sample sheet for creating a static structure pumpdischarge volute, according to one embodiment. The volute shape 531 isincluded, as is central hole 532. Additional material 533 is left on oneedge of the sheet to allow sufficient material to add pump outletfitting 534 during final machining.

FIG. 5 c illustrates a sample static structure pump discharge volute540, according to one embodiment. The inlet fitting 541 receives thefluid into the turbomachine, and the outlet fitting 542 discharges thepressurized fluid. Rotating elements fit within the static structure,rotating about rotation axis 525.

FIG. 6 illustrates a flow diagram for a process for manufacturingrotating elements and static structure of a small scale, high speedturbomachine, according to one embodiment. The process for manufacturinga turbomachine and any additional stationary elements takes as an input610 a design for a turbomachine, for example a Computer Aided Design(CAD) drawing or other three-dimensional representation of theturbomachine including its constituent rotating and non-rotatingelements. The turbomachine is divided up 620 into two dimensionalsheets, each representing a cross section of the turbomachine or anelement of the turbomachine at an appropriate plane or circular orconical or other axisymmetric shell. Each sheet has a specifiedthickness. The sheets are pre-formed 630 into the cross section of therotating element from the design drawing through etching or machining,or another suitable process. The sheets are separated from each other,and are ordered and stacked 640 so as to reproduce the structure of theturbomachine. The stack of sheets is bonded 650 together to bind thesheets together into a single component. The stack may be fusion bondedunder heat and pressure, diffusion bonded, or brazed, depending upon theembodiment. The device is machined 660 to create any additionalstationary elements and to form the turbomachine into the desired shape.In one embodiment, the machining may include electro-discharge machining(EDM).

Blading with Integral Cooling Components

Turbomachines frequently operate at high temperatures. A turbomachineexposed to a temperature above a certain threshold may work lessefficiently or cease to work entirely. This may be due to a number ofdifferent reasons. For example, materials making up the blading,shrouding, housing, or central portions of the rotating element may meltor lose strength at the temperature of the fluid passing through them.Also, thermal expansion of the materials making up the blading,shrouding, and/or housing may cause the clearance between blading andshrouding or housing to decrease or increase in size. A change in theclearance may decrease the efficiency of the turbomachine. If the gapcloses entirely, the turbomachine may cease functioning.

Large turbomachines incorporate integrated cooling features that allowthe rotating elements to process fluids with higher temperatures thanwould be possible if the rotating elements were uncooled. The coolingfeatures are designed to keep the rotating structure temperature wellbelow the temperature of the working fluid. As turbomachines getsmaller, it is more difficult to incorporate integrated cooling featureswhich can assist in cooling the turbomachine at high temperatureoperation. However, the use of bonded metal sheets makes it possible toincorporate integrated cooling features in many embodiments, even atsmall scales.

In one embodiment, the etched metal foil sheets used to construct therotating elements include features that, once stacked and bonded, createcooling flow passages within the structure and blades of the rotatingelement. In one embodiment, the sheets include features that result inporous blading designed to receive and distribute a cooling fluid withinthe rotating element. In one embodiment, the stationary elements of theturbomachine include passages for a cooling fluid to pass nearby andcool the stationary element.

FIGS. 7 a and 7 b illustrate cross sections of a rotating element of aturbomachine manufactured by stacking and bonding metal foil sheets 711such that the sheets form planes perpendicular to the axis or rotation712, and the sheets include features 713, 714 for cooling the rotatingelement. In one embodiment, the rotating element will be an internallycooled axial-flow turbine. In one embodiment, after bonding excessmaterial will be removed to contour 715 to define the blading andturbine disk, as well as to provide access ports 716 for the internalcooling fluid.

FIG. 7 b illustrates a cross section through the cooling features 714,according to one embodiment. In one embodiment, cooling featuresincludes cooling passages 721 and 722, passages 723 for forming jetsinto internal cavity 724 for impingement cooling of the blade leadingedge, and trailing edge slots 725 for directing the cooling air into themain flow path. The external contour 726 of the blade is shown accordingto one embodiment. The cooling features illustrated in FIG. 7B appearcoarser and rougher than they would be in most embodiments, since manymore sheets can be used than can be illustrated successfully, so therewill be substantially higher out-of-sheet-plane resolution within thecooling structures.

FIG. 7 c illustrates a sample sheet used to manufacture the internallycooled axial-flow turbine, according to one embodiment, and includescoolant distribution channels 731, and blade cooling passage 732. Acontour 733 for removing material to define the blades and flowpathgeometry is also illustrated for one embodiment.

In additional embodiments, cooling features are incorporated into radialin-flow and radial out-flow turbines, static structures includingturbine inlet guide vanes, as well as into axial turbines manufacturedusing sheets formed into cylindrical shells. In some embodiments thereare performance advantages because the sheets are in planesapproximately parallel to the flow direction and allow for additionalgeometrical complexity in defining shapes within the planes of thesheets.

FIGS. 7 d and 7 e illustrate examples of this increased flexibility.FIG. 7 d shows cooling passages 741 and trailing edge slot 742, in oneembodiment. In one embodiment, FIG. 7 e shows porous structures 751serving as cooling passages, where increased internal surface area andincreased flow turbulence enhances cooling. FIG. 7 e also shows trailingedge slot 752.

Static Structure

Other examples of static structures which may be part of a turbomachinemay also include blading for exit vanes used in a diffuser locateddownstream of a rotating element, blading for turbine inlet vanesupstream from a turbine inlet, inlet or outlet volutes, and sealingelements. Static structures to be used in conjunction with the smallscale turbomachine may also be manufactured separately from theturbomachine using the same process.

The process described used to create the turbomachine may be alteredinto order to fabricate bearing journals. Fabricating bearings allowsthe turbomachine to incorporate fluid bearings. Examples of fluidbearings include hydrostatic, hydrodynamic, or film bearings.

For very small turbomachinery, in some embodiments it will beadvantageous to include partial emission pumps or compressors or partialadmission turbines. These types of turbomachinery involve staticstructures where a portion of the inlet flow annulus (for turbines) orthe outlet flow annulus (for pumps/compressors) is blocked so as torestrict flow. In one embodiment, a partial emission static structure iscreated by closing a portion of diffusion area 512 (in FIG. 5 a) suchthat flow can only enter the volute over a fraction of the receivingcircumference.

Labyrinth Seals

In some embodiments, it may be beneficial to use labyrinth type seals toprevent excessive fluid leakage. FIG. 8A illustrates a labyrinth seal inaccordance with one embodiment. The labyrinth seal includes a smoothrotating element 873, rotating about axis 895 placed in close proximityto stationary element 874 which includes a number of repeating teeth. Inone embodiment, the teeth are created by alternately layering a numberof thinner layers of a material 871 with a number of thicker layers of asimilar material 872. In one embodiment, a typical thickness of athinner layer would be approximately 0.002 inches, and a typicalthickness of a thicker layer would be approximately 0.008 inches, suchthat the number of teeth per inch is approximately 100. Alternatingthick and thin layers allows for a large number of teeth per length ofseal, which facilitates improved sealing compared to conventionallabyrinth seals. In another embodiment, rotating element 873 may be theshaft of the turbomachine, a sleeve of the shaft, or a material insertedonto the shaft. The rotating element may be made from a differentmaterial than the remainder of the turbomachine. In one embodiment,rotating element 873 is made of PTFE.

The labyrinth seals may be defined by a number of parameters. The length890 indicates the length of the teeth 871 of the labyrinth seal. Thethickness 891 indicates the thickness of the teeth 871. The pitch 892indicates the distance between teeth 871. The gap 893 is the distancebetween the rotating element 873 and the stationary element 874.

FIGS. 8B and 8C illustrate labyrinth seals according other embodiments.The labyrinth seal includes stationary elements 881 and 882 placed incontact with rotating elements 887 and 888. The labyrinth seals of FIG.8 include a set of teeth for each of the stationary and rotatingelements. Smaller teeth on the rotating elements 887 and 888 may becreated by stacking thin layers 883 and 884 with thick layers 885 and886 of similar thicknesses. The smaller teeth are smaller relative totheir counterparts on the stationary elements. The smaller teeth arealigned axially such that the smaller teeth are located in between thelonger teeth of the stationary element. Interlacing the teeth in thismanner improves seal performance by diverting the path of fluid as it isleaking through the seal. In one example, the teeth divert leaking fluidaway from an upstream seal gap away from the next seal gap.

Additional Considerations

In the above description, turbomachines are described as acting uponvarious fluids such as the working fluid and the turbine drive fluid.The described embodiments also function with gases as well as liquids.In some cases, taller blading may be used if the turbomachine isoperating on a gas in order to adjust for reduced density versus aliquid substance. However, the concepts disclosed herein remain the sameregardless of which type of substance is used.

Generally, the turbomachines may be constructed from any solid materialwhich approximately maintains its structure when the turbomachine isoperated at high speed, high temperature, and/or high pressure. Thedescription above makes use of the term “metal foil sheets,” however aturbomachine manufactured according to embodiments of the invention maybe made from a variety of materials, including different metals, metalalloys, other compounds that include metal elements, plastics or otherorganic compounds. Example metals from which the turbomachine may beconstructed include stainless steel, nickel, nickel-based alloys,titanium, titanium-based alloys, brass, aluminum, or aluminum-basedalloys.

The foregoing description of the embodiments of the invention has beenpresented for the purpose of illustration; it is not intended to beexhaustive or to limit the invention to the precise forms disclosed.Persons skilled in the relevant art can appreciate that manymodifications and variations are possible in light of the abovedisclosure.

Finally, the language used in the specification has been principallyselected for readability and instructional purposes, and it may not havebeen selected to delineate or circumscribe the inventive subject matter.It is therefore intended that the scope of the invention be limited notby this detailed description, but rather by any claims that issue on anapplication based hereon. Accordingly, the disclosure of the embodimentsof the invention is intended to be illustrative, but not limiting, ofthe scope of the invention, which is set forth in the following claims.

What is claimed is:
 1. A process for manufacturing a rotating element ofa turbomachine, the method comprising: pre-forming a plurality of sheetsof a material, each sheet comprising a cross section of the rotatingelement of the turbomachine; stacking the sheets in an order toreproduce a structure of the rotating element; bonding the sheetstogether to form the rotating element therewithin; and removing anamount of excess material from the bonded sheets to free the rotatingelement therefrom, wherein stacking the sheets in an order to reproducethe structure of the rotating element comprises stacking the sheets atan angle that is not 0 or 90 degrees with respect to the axis of therotating element.
 2. A process for manufacturing a rotating element of aturbomachine, the method comprising: pre-forming a plurality of sheetsof a material, each sheet comprising a cross section of the rotatingelement of the turbomachine; stacking the sheets in an order toreproduce a structure of the rotating element; bonding the sheetstogether to form the rotating element therewithin; and removing anamount of excess material from the bonded sheets to free the rotatingelement therefrom, wherein stacking the sheets in an order to reproducethe structure of the rotating element comprises forming the sheets intoaxisymmetric shells prior to bonding.
 3. A turbomachinery componentconfigured to rotate during operation, comprising: a plurality ofpreconfigured metal sheets that when bonded together define a hub, ashroud, a plurality of blades, and a plurality of fully formed primaryflow paths for pumping or compressing a working fluid or gas or forextracting energy from the working fluid or gas, wherein the pluralityof blades extend from the hub to the shroud and are integrally formedwith the hub and the shroud by the bonded metal sheets, wherein theplurality of preconfigured metal sheets are stacked at an angle that isnot 0 degrees and not 90 degrees with respect to a centerline axis ofthe hub.
 4. A turbomachinery component configured to rotate duringoperation, comprising: a plurality of preconfigured metal sheets thatwhen bonded together define a hub, a shroud, a plurality of inducerblades, a plurality of impeller blades, and a plurality of fully formedprimary flow paths for pumping or compressing a working fluid or gas orfor extracting energy from the working fluid or gas, wherein theplurality of inducer blades and the plurality of impeller blades extendfrom the hub to the shroud and are integrally formed with the hub andthe shroud, wherein the plurality of preconfigured metal sheets arestacked at an angle that is not 0 degrees and not 90 degrees withrespect to a centerline axis of the hub.
 5. A turbomachinery componentconfigured to rotate during operation, comprising: a plurality ofpreconfigured metal sheets that when bonded together define a hub, ashroud, a plurality of blades, and a plurality of fully formed primaryflow paths for pumping or compressing a working fluid or gas or forextracting energy from the working fluid or gas, wherein the pluralityof blades extend from the hub to the shroud and are integrally formedwith the hub and the shroud by the bonded metal sheets, wherein at leastone of the preconfigured metal sheets defines a portion of each of thehub, the shroud, the plurality of blades, and the plurality of fullyformed primary flow paths, wherein a discharge diameter of the blades is0.4 inches to 3 inches, wherein a blade height of each of the blades atthe discharge diameter is 0.1 inch or less, wherein the blade height ofeach of the blades varies from an inlet end to a discharge end of theblades, wherein the plurality of preconfigured metal sheets are stackedat an angle that is not 0 degrees and not 90 degrees with respect to acenterline axis of the hub.